mob update

Changed the models for undead necromacer to a custom skin

Changed the name of withered beserker to withering beserker

Changed the name of withered tank to withering tank

Changed the models for withering tank/beserker to a custom skin

Changed the model of the withered king to a custom skin

Fixed the name of the undead necromancer

Fixed some drops of the undead necromancer

changed the model for the withered skeleton to be a custom skin

removed the gold helmet from the withered king as it has a custom skin

changed the model from the crypt guard to a custom skin

possibly fixed names if they were missing from mobs